package p2000;

import java.util.Scanner;

public class Main2004成绩转换 {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextInt()) {
            int n = scanner.nextInt();

            if (n < 0 || n > 100) {
                System.out.println("Score is error!");
            } else {
                if (n <= 60) {
                    System.out.println("E");
                } else if (n <= 70) {
                    System.out.println("D");
                } else if (n <= 80) {
                    System.out.println("C");
                } else if (n <= 90) {
                    System.out.println("B");
                } else {
                    System.out.println("A");
                }
            }
        }
    }

}
